Care to guess how much power Mercedes-AMG's new four-cylinder engine produces? If you're thinking of a figure between 200 or 300, we won't blame you. It is a four-cylinder engine after all. However, the German marque's new M139 engine is capable of producing a lot more than that.

In fact, the 2.0-liter turbo unit has a max output of 421 horsepower and 500 Nm of torque, making it the most powerful four-cylinder engine ever offered from the factory. Compared to its predecessor, the M133, the new unit produces an additional 41 horsepower and 25 Nm of torque.

Mercedes-AMG 2.0L Turbo image

Going down to the specs, the new M139 will be available in two output versions: 421 horsepower for the S-variants and 387 horsepower for the standard models. Both units use a twin-scroll turbocharger, with the S-variant producing 30.5 psi (2.1 bar) of boost and the standard model producing 27.6 psi (1.9 bar).

Aside from a new turbo, the M139 features a new closed-deck aluminum block which only weighs 160.5kg and is combined with a forged crankshaft and pistons. Interestingly, the engine is oriented 180 degrees opposite its predecessor with the exhaust manifold and turbo now facing the firewall. Mercedes claims that this setup helps reduce complex turns in the piping and improves gas flow. Much like their V8 engines, the M139 is assembled by a single person.

Mercedes-AMG 2.0L Turbo image

Unlike other high-power four-cylinder engines in the past, the new engine won't be used for a limited-edition model. Instead, the new M139 engine will power the upcoming Mercedes-AMG CLA 45, GLA 45, and A 45 models which are slated to make their debut later this year. All-wheel drive with drift mode will come standard as well.

With the engine and specs already revealed, we're excited to see what the upcoming A 45 AMG can do.